A man who viciously slashed his ex-wife in front of their three kids on the Lower East Side last year was thrown in prison Wednesday for 21-1/2-to-23 years.

John Woody, 41, pleaded guilty in September to assault, burglary and other charges stemming from the brutal attack.

“John Woody launched a campaign of terror against his ex-wife, culminating in a vicious attack in front of their three young children,” said District Attorney Cy Vance. “Not only did Woody physically and emotionally scar the victim, his violent actions also scarred the children who were forced to witness an unthinkable attack against their mother.”

Woody followed his ex-wife into her apartment building then hacked up her face, neck and back as their children watched in horror on July 8, 2013.